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authorViresh Kumar <viresh.kumar@linaro.org>2013-10-16 23:58:10 +0200
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2013-10-16 23:58:10 +0200
commit1bab64d50e09706ee2e634b2df3c53346f0a0dbb (patch)
treeb7df2d323eb358e1633506ed360a191a41e1ae8d /drivers/cpufreq/acpi-cpufreq.c
parent076dec90fc32c830184b0f0fa1842a6de1199bc6 (diff)
downloadleg-kernel-1bab64d50e09706ee2e634b2df3c53346f0a0dbb.tar.gz
acpi-cpufreq: Add comment under ACPI_ADR_SPACE_SYSTEM_IO case
policy->cur is now set by cpufreq core when cpufreq_driver->get() is defined and so drivers aren't required to set it. When space_id is ACPI_ADR_SPACE_SYSTEM_IO for acpi cpufreq driver it doesn't set ->get to a valid function pointer and so policy->cur is required to be set by driver. This is already followed in acpi-cpufreq driver. This patch adds a comment describing why we need to set policy->cur from driver. Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpufreq/acpi-cpufreq.c')
-rw-r--r--drivers/cpufreq/acpi-cpufreq.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
index a8dac7b53042..a1717d7367c1 100644
--- a/drivers/cpufreq/acpi-cpufreq.c
+++ b/drivers/cpufreq/acpi-cpufreq.c
@@ -837,7 +837,12 @@ static int acpi_cpufreq_cpu_init(struct cpufreq_policy *policy)
switch (perf->control_register.space_id) {
case ACPI_ADR_SPACE_SYSTEM_IO:
- /* Current speed is unknown and not detectable by IO port */
+ /*
+ * The core will not set policy->cur, because
+ * cpufreq_driver->get is NULL, so we need to set it here.
+ * However, we have to guess it, because the current speed is
+ * unknown and not detectable via IO ports.
+ */
policy->cur = acpi_cpufreq_guess_freq(data, policy->cpu);
break;
case ACPI_ADR_SPACE_FIXED_HARDWARE: